This invention relates to an improved cooling and/or heating system. The air conditioning systems currently in use in many homes and in automobiles employ a two-phase refrigeration system. The components are complicated and also expensive. These systems also require an expansion valve and a number of high pressure lines and suitable fittings.
There is concern over the ozone depletion potential of many existing refrigerants. This makes it desirable to use a non-polluting, single-fluid refrigeration system such as one which uses air. Some rotor/vane compression systems for refrigeration and air conditioning using air were patented from 1969 to 1980. These were mainly single-stage unit designs for the cooling of automobiles.
In such units, the rotor has vanes which are biased outwardly so the edges contact the inner wall of the housing as the rotor is rotated. The housing is shaped such that in about one-half of a rotation the incoming air is compressed. The compressed air exits the unit and is cooled somewhat. It then re-enters the expansion side of the unit and is expanded to obtain cool air. The rotating vanes and the inner wall of the housing form chambers of continually varying size. By proper arrangement, this permits compression on one side of the unit and expansion on the other.
Some problems exist with these units related to the nature of rotary vane compressors. For rotary vane compressors to compete with existing refrigerant and air conditioning units, they must operate maintenance free for five to ten years, for example. The vane tip wear on rotary cooling and heating systems ultimately resulted in maintenance after two to three years. If precisely machined vanes were guided using bearings on rails, vane tip wear was minimized. However, these parts increased the cost of the unit. Also, when the machine heated up during operations, the tips no longer remained in contact with the housing. This caused leakage and a drop in efficiency. To my knowledge, the last attempt at a solution to this tip wear problem was described in a patent issued to Thomas C. Edwards on Dec. 30, 1980, U.S. Pat. No. 4,241,591 for a unit using amorphous carbon and magnesium parts.
The use of air as a refrigerant as a substitute for the potentially ozone damaging refrigerants presently used is highly desirable. There was an effort in the late 60's and through the 70's to produce a refrigeration system using air. However, they all had certain shortfalls, and to my knowledge no major effort has been made since then in this area. It is therefore clear that there is a need for improved or new designs for compression/expansion units which would make the use of air as a refrigerant very attractive and efficient and comparable in line to the present commercial systems using freon or other type refrigerant in the two-stage processes.